nofollow
nofollow is an instruction within the HTML code which instructs search engines not to include references to other pages in the calculation of their link popularity . The nofollow statement can be used in two ways:
- on the one hand as a microformat (in full HTML notation
rel="nofollow") within hyperlinks - on the other hand as a meta tag within the page header of a document.
Not all search engines follow these instructions.
The deliberate avoidance of nofollow is advertised in search engine marketing with the terms dofollow or “follow link”.
syntax
Hyperlink
A normal hyperlink, for example to the page example.com , is marked as follows in the HTML source code:
<a href="http://example.com/">Beispiel</a>
If the value nofollowfor the relattribute (of Engl. Relationship: relationship, relationship) is to be used, the hyperlink is supplemented as follows:
<a href="http://example.com/" rel="nofollow">Beispiel</a>
With this method, individual links can be marked individually.
Meta tag
<meta name="robots" content="nofollow" />
nofollow is a supplement to the so-called meta tag robots , which can also nofollowcontain a value . This affects all links on a website.
Origin, function and effect
The value nofollowfor the relattribute was introduced by Google in 2005 and adopted almost simultaneously by all major search engines ( Yahoo , MSN ). The purpose of this information is to avoid the effects of spam.
Many spammers try to increase their link popularity or their PageRank value by frequently placing links on the websites they advertise and thereby improve the position of their website in search engine search results ( search engine spamming ). Since such links are undesirable, the attribute is automatically added to all links in many places where visitors can add links on their own (such as comments in blogs ) rel="nofollow". The links marked in this way are then not used by the search engines to calculate the link popularity, thus preventing misuse.
Further areas of application
In addition to marking suspected link spam , the use of nofollow can also be useful in other cases in which link tracking by search engine robots is undesirable and would only cause unnecessary data traffic . Examples are links that lead to print views or trigger evaluation and other feedback functions. However, the behaviors of the search engines in relation to are different and some also follow links with the attribute.
rel="nofollow"
standardization
The value nofollowis a non-standardized extension of the relattribute. The extension by values defined by the author is permitted in HTML 4.01 and thus also XHTML 1.0. The meta tag robots, on the other hand, is defined in the Robots Exclusion Standard .
criticism
Critics of the nofollow links complain that the nofollows change the search engine evaluation results. They see this as a distortion that leads to loss of meaningfulness. The argument that it is not the task of individual websites to promote or ensure the quality of search engine rating systems is put forward by both critics and supporters. Critics argue that the website operator is not responsible for relieving search engines of the trouble of distinguishing between potential spam and desired links. Proponents use the same argument and state that they do not see it as their job to serve as a source for search engines to calculate the ranking of other websites.
The way in which the well-known search engines follow the information is cause for speculation, as it is not an effective block, but in practice only a recommendation. In particular, the indexing of the link target cannot be effectively excluded.
See also
Individual evidence
- ↑ Specification of rel = "nofollow" in the Microformats Wiki (English)
- ^ Google: Preventing comment spam. January 18, 2005, accessed May 20, 2016 .
- ↑ Development of the link award in the "Online Marketing Lexicon". Retrieved March 26, 2019 .
- ↑ Link types in the HTML 4.01 standard (English)
- ↑ META tag in the Robots Exclusion Standard (English)